Etching solution for multiple layer of copper and molybdenum and etching method using the same

ABSTRACT

An etching solution for a multiple layer of copper and molybdenum includes: about 5% to about 30% by weight of a hydrogen peroxide; about 0.5% to about 5% by weight of an organic acid; about 0.2% to about 5% by weight of a phosphate; about 0.2% to about 5% by weight of a first additive having nitrogen; about 0.2% to about 5% by weight of a second additive having nitrogen; about 0.01% to about 1.0% by weight of a fluoric compound; and de-ionized water making a total amount of the etching solution 100% by weight.

[0001] This application claims the benefit of Korean Patent ApplicationNos. 2002-79211, filed on Dec. 12, 2002 and 2003-82375, filed on Nov.19, 2003, which are hereby incorporated by references for all purposesas if fully set forth herein.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an etching solution for a metallayer, and more particularly, to an etching solution for acopper-molybdenum layer and an etching method using the same.

[0004] 2. Discussion of the Related Art

[0005] In general, in order to form a metal line on a substrate for asemiconductor device, several steps are required such as forming a metallayer on a substrate using sputtering, forming a photoresist (PR)pattern on the metal layer by coating, exposure and development andetching the metal layer with a cleaning step before and/or after each ofthe steps. The metal layer is patterned using the PR pattern as anetching mask during the etching step. A dry etching method using plasmaor wet etching method using an etching solution may be used for theetching step.

[0006] Recently, the resistance of a metal layer has been an issue forsemiconductor devices. Resistance of a metal layer is a crucial factorfor a RC (resistance-capacitance) signal delay component insemiconductor devices. Likewise, resistance of metal layers should beconsidered to increase the panel size and resolution of thin filmtransistor liquid crystal display (TFT-LCD) devices. For a large-sizeTFT-LCD device, the RC signal delay should be reduced and a materialhaving low resistivity should be developed. In general, metals such aschromium (Cr) (resistivity of about 12.7×10⁻⁸ Ωm), molybdenum (Mo)(resistivity of about 5×10⁻⁸ Ωm), aluminum (Al) (resistivity of about2.65×10⁻⁸ Ωm) and alloys thereof have been used for the metal layers ofTFT-LCD devices. However, those metals are not suitable for gate anddata lines of a large-size TFT-LCD device due to their high resistance.As a result, copper (Cu) has been suggested as a material for a metalline. Copper (Cu) has a lower resistivity than aluminum (Al) andchromium (Cr), and has other advantages for the environment. However,copper has disadvantages with respect to the photolithographic process,which includes PR coating and patterning steps. Moreover, copper has apoor adhesion to an insulating layer including silicon (Si).

[0007] To overcome the disadvantages of a copper (Cu) single layer, amultiple layer including copper (Cu) has been suggested. For example, amultiple layer of copper (Cu) and titanium (Ti) has been evaluated as ametal line for a large-size TFT-LCD device. An etching solution for themultiple layer of copper (Cu) and titanium (Ti) has already exist andseveral other etching solutions have been suggested. However, since theetching solution for the multiple layer of copper (Cu) and titanium (Ti)includes fluoric ion due to a chemical property of titanium (Ti), layershaving silicon in TFT-LCD devices (e.g., a glass substrate, an activelayer of silicon, an insulating layer of silicon nitride (SiN_(x)) orsilicon oxide (SiO₂)) are also etched. This undesired etching of thelayers including silicon complicates the fabricating process of theTFT-LCD devices.

[0008] Accordingly, a multiple layer of copper (Cu) and molybdenum (Mo)is suggested. The multiple layer of copper (Cu) and molybdenum (Mo) mayhave properties equal to or better than the multiple layer of copper(Cu) and titanium (Ti) by controlling a thickness ratio. Moreover, sincefluoric ions do not have a direct influence on the etching of themultiple layer of copper (Cu) and molybdenum (Mo), only a small amountof fluoric ions may be added to an etching solution for the multiplelayer of copper (Cu) and molybdenum (Mo) such that a layer includingsilicon is not etched.

[0009] An etching solution including phosphoric acid, nitric acid andacetic acid for the multiple layer including copper (Cu) is disclosed ina published patent No. KP 1999-0017836, and an etching solutionincluding iron chloride (III) hexa-hydride and hydrofluoric acid for amultiple layer including copper (Cu) is disclosed in a published patentNo. KP 2000-0032999. However, when these etching solutions are used toetch a multiple layer of copper (Cu) and molybdenum (Mo), severaldrawbacks exist. First, etching speed is too high to control the etchingstep so that process margin is insufficient. Second, since a taper angleof the cross-sectional profile of the etched multiple layer is equal toor greater than about 90°, device defects or inferiority may occurduring a subsequent process. Third, straightness of the etched multiplelayer is not good. Fourth, when the etching solution including ironchloride (III) hexa-hydride and hydrofluoric acid is used, a layerincluding silicon is undesirably etched as in the case of the etchingsolution for a multiple layer of copper (Cu) and titanium (Ti).

[0010]FIG. 1A is a perspective scanning electron microscope (SEM) imageshowing a pattern of copper (Cu) and molybdenum (Mo) formed by etchingwith an etching solution including phosphoric acid, nitric acid andacetic acid, and FIG. 1B is a perspective scanning electron microscope(SEM) image showing a pattern of copper (Cu) and molybdenum (Mo) formedby etching with an etching solution including iron chloride (III)hexa-hydride and hydrofluoric acid. As shown in FIGS. 1A and 1B, thepattern of copper (Cu) and molybdenum (Mo) has a poor profile and a poorstraightness. Especially, in FIG. 1B, the glass substrate has a roughtop surface because hydrofluoric acid of the etching solution etches theglass substrate which includes silicon.

[0011] Another etching solution which includes hydrogen peroxide issuggested for etching a multiple layer of copper (Cu) and molybdenum(Mo). However, the etching solution has a first optimum pH value ofabout 2 to about 4 for copper (Cu) and a second optimum pH value ofabout 4 to about 7 for molybdenum (Mo). As a result, the molybdenum (Mo)layer may remain as a residue when the etching solution is controlled tohave the first optimum pH value for copper (Cu), and etching speed ofthe copper (Cu) layer is severely reduced when the etching solution iscontrolled to have the second optimum pH value for molybdenum (Mo).

[0012]FIG. 2A is a cross-sectional scanning electron microscope (SEM)image showing a pattern of copper (Cu) and molybdenum (Mo) formed byetching with an etching solution including hydrogen peroxide, FIG. 2B isa perspective scanning electron microscope (SEM) image showing a patternof copper (Cu) and molybdenum (Mo) formed by etching with an etchingsolution including hydrogen peroxide, anid FIG. 2C is a perspectivescanning electron microscope (SEM) image showing a substrate afteretching with an etching solution including hydrogen peroxide. As shownin FIGS. 2A and 2B, the pattern of copper (Cu) and molybdenum (Mo) has arelatively good profile and a good straightness. As shown in FIG. 2C,however, a large number of molybdenum (Mo) residues are observed on thesubstrate because the etching solution having a pH value suitable forcopper (Cu) does not etch molybdenum (Mo) completely.

SUMMARY OF THE INVENTION

[0013] Accordingly, the present invention is directed to an etchingsolution for a multiple layer of copper (Cu) and molybdenum (Mo) thatsubstantially obviates one or more of problems due to limitations anddisadvantages of the related art.

[0014] An advantage of the present invention is to provide an etchingsolution that etches a multiple layer of copper (Cu) and molybdenum (Mo)almost without molybdenum (Mo) residues, and an etching method using thesame.

[0015] Another advantage of the present invention is to provide anetching solution for a multiple layer of copper (Cu) and molybdenum (Mo)that provides a controllable etching speed, a taper angle of about 30°to about 60°, an excellent straightness, a long lifetime and a pH valueof about 2 to about 4 for copper (Cu), and an etching method using thesame.

[0016] Another advantage of the present invention is to provide anetching solution for copper (Cu) that has low resistivity and preventsenvironmental pollution.

[0017] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.These and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0018] To achieve these and other advantages and in accordance with thepurpose of the present invention, as embodied and broadly described, anetching solution for a multiple layer of copper and molybdenum includes:about 5% to about 30% by weight of a hydrogen peroxide; about 0.5% toabout 5% by weight of an organic acid; about 0.2% to about 5% by weightof a phosphate; about 0.2% to about 5% by weight of a first additivehaving nitrogen; about 0.2% to about 5% by weight of a second additivehaving nitrogen; about 0.01% to about 1.0% by weight of a fluoriccompound; and de-ionized water making a total amount of the etchingsolution 100% by weight.

[0019] In another aspect of the present invention, an etching method fora multiple layer of copper and molybdenum includes: forming the multiplelayer of copper and molybdenum on a substrate; forming a photoresistpattern on the multiple layer; and etching the multiple layer with anetching solution including: about 5% to about 30% by weight of ahydrogen peroxide; about 0.5% to about 5% by weight of an organic acid;about 0.2% to about 5% by weight of a phosphate; about 0.2% to about 5%by weight of a first additive having nitrogen; about 0.2% to about 5% byweight of a second additive having nitrogen; about 0.01% to about 1.0%by weight of a fluoric compound; and a de-ionized water making a totalamount of the etching solution 100% by weight.

[0020] In another aspect, a composition for etching a multiple layer ofcopper and molybdenum includes: about 5% to about 30% by weight of ahydrogen peroxide; about 0.5% to about 5% by weight of an organic acid;about 0.2% to about 5% by weight of a phosphate; about 0.2% to about 5%by weight of a first additive having nitrogen; about 0.2% to about 5% byweight of a second additive having nitrogen; and about 0.01% to about1.0% by weight of a fluoric compound.

[0021] In another aspect, a method of fabricating an array substrate fora liquid crystal display device, comprising: forming a gate electrodeand a gate line on a substrate; forming a first insulating layer on thegate electrode and the gate line; forming a semiconductor layer on thefirst insulating layer; and forming source and drain electrodes on thesemiconductor layer and a data line crossing the gate line, the sourceand drain electrode being spaced apart from each other, the sourceelectrode being connected to the data line, the gate line and the dataline defining a pixel region, wherein at least one of the gate line andthe data line is a multiple layer of copper and molybdenum, and theetching of the multiple layer is performed with an etching solutionincluding: about 5% to about 30% by weight of a hydrogen peroxide; about0.5% to about 5% by weight of an organic acid; about 0.2% to about 5% byweight of a phosphate; about 0.2% to about 5% by weight of a firstadditive having nitrogen; about 0.2% to about 5% by weight of a secondadditive having nitrogen; about 0.01% to about 1.0% by weight of afluoric compound; and a de-ionized water making a total amount of theetching solution 100% by weight.

[0022] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0024] In the drawings:

[0025]FIG. 1A is a perspective scanning electron microscope (SEM) imageshowing a pattern of copper (Cu) and molybdenum (Mo) formed by etchingwith an etching solution including phosphoric acid, nitric acid andacetic acid;

[0026]FIG. 1B is a perspective scanning electron microscope (SEM) imageshowing a pattern of copper (Cu) and molybdenum (Mo) formed by etchingwith an etching solution including iron chloride (III) hexa-hydride andhydrofluoric acid;

[0027]FIG. 2A is a cross-sectional scanning electron microscope (SEM)image showing a pattern of copper (Cu) and molybdenum (Mo) formed byetching with an etching solution including hydrogen peroxide;

[0028]FIG. 2B is a perspective scanning electron microscope (SEM) imageshowing a pattern of copper (Cu) and molybdenum (Mo) formed by etchingwith an etching solution including hydrogen peroxide;

[0029]FIG. 2C is a perspective scanning electron microscope (SEM) imageshowing a substrate after etching with an etching solution includinghydrogen peroxide;

[0030]FIGS. 3A to 3F are schematic cross-sectional views illustrating anetching process of a multiple layer according to an embodiment of thepresent invention;

[0031]FIG. 4A is a cross-sectional scanning electron microscope (SEM)image showing a pattern of copper (Cu) and molybdenum (Mo) formed byetching with an etching solution according to an embodiment of thepresent invention;

[0032]FIG. 4B is a perspective scanning electron microscope (SEM) imageshowing a pattern of copper (Cu) and molybdenum (Mo) formed by etchingwith an etching solution according to an embodiment of the presentinvention;

[0033]FIG. 4C is a perspective scanning electron microscope (SEM) imageshowing a substrate after etching with an etching solution according toan embodiment of the present invention;

[0034]FIG. 5A is a schematic view showing an array substrate for aliquid crystal display device fabricated by using an etching solutionaccording to an embodiment of the present invention; and

[0035]FIG. 5B is a cross-sectional view taken along the line “VB-VB” ofFIG. 5A.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0036] Reference will now be made in detail to embodiments of thepresent invention, example of which is illustrated in the accompanyingdrawings. Wherever possible, similar reference numbers will be usedthroughout the drawings to refer to the same or like parts.

[0037] A multiple layer of copper (Cu) and molybdenum (Mo) includes adouble layer of a lower copper (Cu) layer and an upper molybdenum (Mo)layer, a double layer of a lower molybdenum (Mo) layer and an uppercopper (Cu) layer, and a triple layer of a bottom molybdenum (Mo) layer,a middle copper (Cu) layer and a top molybdenum (Mo) layer. In otherwords, the multiple layer of copper (Cu) and molybdenum (Mo) includes aplurality of copper (Cu) layers and a plurality of molybdenum (Mo)layers alternately interposed therebetween. The structure of themultiple layer of copper (Cu) and molybdenum (Mo) is determined by amaterial for an upper layer or a lower layer of the multiple layer andadhesion between the layers. The thickness of the copper (Cu) layer andthe thickness of the molybdenum (Mo) layer may not be limited and may beindependent of each other. Accordingly, when the thickness of molybdenum(Mo) layer is zero, the multiple layer means a single layer of copper(Cu).

[0038] An etching solution for a multiple layer of copper (Cu) andmolybdenum (Mo) according to the present invention may include hydrogenperoxide, an organic acid, phosphate, a first additive includingnitrogen, a second additive including nitrogen and fluoric compound,which can be prepared by a conventional method and have a puritysufficient for a fabricating process of a semiconductor device, withde-ionized water as solvent. The de-ionized water may have a resistanceover about 18 MΩ/cm. Other typical additives used for an etchingsolution may be added.

[0039] Hydrogen peroxide and organic acid are ingredients for etchingcopper (Cu) and molybdenum (Mo), and have a purity sufficient for afabricating process of a semiconductor device. For example, hydrogenperoxide and organic acid have metallic impurity density less than 10ppb (part per billion). Various kinds of organic acid may be usedwithout a specific limitation. For example, acetic acid, butanoic acid,citric acid, formic acid, gluconic acid, glycolic acid, malonic acid,oxalic acid, pentanoic acid and other water-soluble organic acid may beapplied as an organic acid.

[0040] Organic acid controls the pH value of the etching solution sothat the copper (Cu) and molybdenum (Mo) can be etched. If the etchingsolution includes only hydrogen peroxide without organic acid, theetching solution can not etch copper (Cu). The etching solutionincluding organic acid may have an pH value of about 0.5 to about 4.5.

[0041] Phosphate controls a cross-sectional profile of the etchedmultiple layer, which relates to a taper angle of the etched multiplelayer. Various kinds of phosphate may be used without a specificlimitation. For example, sodium dihydrogen phosphate, potassiumdihydrogen phosphate, where at least one hydrogen of phosphoric acid issubstituted with alkali metal or alkaline earth metal, may be used asphosphate. Phosphate reduces an electric effect between copper (Cu) andmolybdenum (Mo) to prevent the so-called “undercut phenomenon”. Forexample, in a case where a double layer of a upper copper (Cu) layer anda lower molybdenum (Mo) layer is etched, the lower molybdenum (Mo) layeris etched away by the etching solution in a cross-sectional view, whenthe undercut phenomenon occurs. If the etching solution does not includephosphate, the upper copper (Cu) layer may be lifted off because thelower molybdenum (Mo) is nearly etched way.

[0042] The first additive including nitrogen controls etching speed of amultiple layer of copper (Cu) and molybdenum (Mo) to reduce criticaldimension (“CD”) loss of patterns, thereby to improve fabricationmargin. Various kinds of additives may be used without a specificlimitation. For example, aminotetrazole, imidazole, indole, purine,pyrazole, pyridine, pyrimidine, pyrrole, pyrrolidine, pyrroline andother water-soluble cyclic amine compound may be used as the firstadditive. If the etching solution does not include the first additive,etching speed may not be controllable, and a suitable width of patternsmay not be obtained. Accordingly, possibility of device defects anddegradation increases, and fabrication margin is reduced. These maycause problems in mass production.

[0043] Even though the second additive including nitrogen does notdirectly relate to a cross-sectional profile or etching speed, thesecond additive prevents a self-decomposition reaction of hydrogenperoxide, which may occur while the etching solution is stored, andmaintains a uniform etching property of the etching solution even afterthe etching solution is used many times. Various kinds of additives maybe used without a specific limitation. Water-soluble compounds includingan amino group or a carboxyl group, for example, alanine, aminobutyricacid, glutamic acid, glycine, iminodiacetic acid, nitrilotriacetic acid,sarcosine and their derivatives, maybe used as the second additive. Ingeneral, when a solution including hydrogen peroxide is stored, aself-decomposition reaction of hydrogen peroxide may occur. Thus, it ishard to store a solution including hydrogen peroxide for a long time,and there is even a possibility of explosion of a vessel containing thesolution. However, if the second additive including nitrogen is added tothe etching solution, the decomposition speed of hydrogen peroxide canbe reduced by about a tenth of its original value. Accordingly, theetching solution which includes hydrogen peroxide can be stored for alonger time with reliability. Moreover, since the second additiverepresses activation of copper (Cu) ions and molybdenum (Mo) ions, whichare generated through a chelation reaction during the etching of copper(Cu) and molybdenum (Mo), an additional reaction due to the ions may beprevented. As a result, a uniform etching property may be maintainedeven after the etching solution is used many times. Especially, if alarge number of copper (Cu) ions exist in the etching solution withoutthe second additive, copper (Cu) ions form a passivation layer, and thepassivation layer is oxidized to have black color. The etching solutionwithout the second additive does not etch well the oxidized passivationlayer of copper (Cu) ions. However, since the second additive repressesactivation of copper (Cu) ions, the passivation layer of copper (Cu)ions is not formed when the second additives is added into the etchingsolution.

[0044] A fluoric compound is a main ingredient of an etching solutionaccording to the present invention. The fluoric compound removes,residues which are generated in the etching solution when copper (Cu)and molybdenum (Mo) are simultaneously etched. Various kinds of fluoriccompounds may be used without a specific limitation. A compound capableof being dissociated into a fluoric ion or polyatomic fluoric ion in asolution, for example, ammonium fluoride, sodium fluoride, potassiumfluoride and their bifluoric compound such as ammonium bifluoride,sodium bifluoride and potassium bifluoride, may be used as fluoriccompound. In general, an etching solution having a first pH value ofabout 2 to about 4 has an excellent etching property for copper (Cu),while an etching solution having a second optimum pH value of about 5 toabout 7 has an excellent etching property for molybdenum (Mo). To etchcopper (Cu) and molybdenum (Mo) together, an etching solution may beadjusted to have one of the first and second optimum pH values.Typically, the pH value of the etching solution is determined accordingto the thicker layer. Since a copper (Cu) layer is generally thickerthan a molybdenum (Mo) layer, the etching solution may have the first pHvalue of about 2 to about 4. The etching solution having the first pHvalue of about 2 to about 4 etches well copper (Cu), and-also etchesmolybdenum (Mo) with a relatively slow etching speed. However,molybdenum (Mo) generates residues in the form of a particle due to itsown property during an etching step. The residues remain on a glasssubstrate or a lower layer, and may become the cause of an electricalshort or brightness degradation. The fluoric compound removes themolybdenum (Mo) residues in the etching solution. Since the fluoriccompound etches the glass substrate and a layer including silicon, theetching solution may include a small amount of fluoric compound suchthat the glass substrate and the layer including silicon are not etched.For example, about 0.01% to about 1.0% by weight of fluoric compound maysufficiently remove the molybdenum (Mo) residues and may not etch theglass substrate and the layer including silicon.

[0045] A conductive line having a multiple-layers of copper (Cu) andmolybdenum (Mo) may be obtained by using an etching solution accordingto the present invention. A semiconductor device may be interposedbetween the substrate and the layers of copper (Cu) and molybdenum (Mo).The semiconductor device may be fabricated through a repetition ofphotolithographic process and deposition process. In the case of asemiconductor device for a display device such as a liquid crystaldisplay (LCD) device or a plasma display panel (PDP), a dielectric layerand a semiconductor layer including amorphous silicon layer or apolycrystalline silicon layer may be deposited using a chemical vapordeposition (CVD) apparatus, and a conductive layer may be depositedusing a sputter apparatus. A gate line and a data line including sourceand drain electrodes of a thin film transistor (TFT) for the LCD devicemay be formed to have a multiple layers of copper (Cu) and molybdenum(Mo) using an etching solution according to the present invention. Thus,the RC signal delay of the LCD device may be minimized, and the LCDdevice may be increased in size.

[0046]FIGS. 3A to 3F are schematic cross-sectional views illustrating anetching process of a multiple layer according to an embodiment of thepresent invention.

[0047] In FIG. 3A, a molybdenum (Mo) layer 12 and a copper (Cu) layer 14are sequentially formed on a substrate 10. The molybdenum (Mo) layer 12and the copper (Cu) layer 14 constitute a multiple layer 20 of copper(Cu) and molybdenum (Mo). The molybdenum (Mo) layer 12 may have athickness of about 50 Å to about 200 Å and the copper (Cu) layer 14 mayhave a thickness of about 1500 Å to about 2000 Å. Although not shown inFIG. 3A, a semiconductor device such as a thin film transistor (TFT) maybe formed between the substrate 10 and the molybdenum (Mo) layer 12through repetition of a photolithographic process and a depositionprocess. The TFT includes a gate electrode, a gate insulating layer, anactive layer, an ohmic contact layer, a source electrode, and a drainelectrode. A metallic material may be used for the gate electrode, thesource electrode, and the drain electrode. An inorganic material such assilicon nitride (SiN_(x)) and silicon oxide (SiO₂) may be used for thegate insulating layer. Intrinsic amorphous silicon or intrinsicpolycrystalline silicon may be used for the active layer. Impurity-dopedamorphous silicon or impurity-doped polycrystalline silicon may be usedfor the ohmic contact layer. A cleaning process may be performed beforeand/or after each photolithographic process and deposition process.

[0048] In FIG. 3B, a photoresist (PR) layer 16 is formed on the copper(Cu) layer 14. The PR layer may be a positive type or a negative type.

[0049] In FIG. 3C, a PR pattern 16 a is obtained by exposing anddeveloping the PR layer 16 (of FIG. 3B). Even though not shown in FIG.3C, a mask is disposed over the PR layer 16 (of FIG. 3B) and the PRlayer 16 (of FIG. 3B) is irradiated through the mask. The exposedportion of the PR layer 16 (of FIG. 3B) is removed by the developmentfor the positive type PR, while the exposed portion of the PR layer 16(of FIG. 3B) remains after the development for the negative type PR.Additional steps such as ashing and annealing may be further performed.

[0050] In FIG. 3D, the copper (Cu) layer 14 (of FIG. 3B) is etched withan etching solution to form a copper (Cu) pattern 14 a. The etchingsolution may include about 10% by weight of hydrogen peroxide, about 2%by weight of organic acid, about 1% by weight of phosphate, about 0.5%by weight of a first additive including nitrogen, about 0.5% by weightof a second additive, about 0.05% by weight of a fluoric.compound andabout 85.95% by weight of de-ionized water.

[0051] In FIG. 3E, the molybdenum (Mo) layer 12 (of FIG. 3B) issequentially etched with the same etching solution to form a molybdenum(Mo) pattern 12 a. The copper (Cu) layer 14 (of FIG. 3B) and themolybdenum (Mo) layer 16 (of FIG. 3B) may be etched by a dipping methodor a spray method. An etching temperature may be determined according toprocess conditions. For example, the copper (Cu) layer 14 (of FIG. 3B)and the molybdenum (Mo) layer 16 (of FIG. 3B) may be etched under atemperature of about 30° C. The etching time depends on the etchingtemperature. For example, the copper (Cu) layer 14 (of FIG. 3B) and themolybdenum (Mo) layer 16 (of FIG. 3B) may be etched for about 30 secondsto about 180 seconds.

[0052] In FIG. 3F, after etching the copper (Cu) layer 14 (of FIG. 3B)and the molybdenum (Mo) layer 16 (of FIG. 3B), the PR pattern 16 a (ofFIG. 3C) is stripped and a pattern 20 a of copper (Cu) and molybdenum(Mo) is obtained. The pattern 20 a of copper (Cu) and molybdenum (Mo)may have a taper angle.

[0053] The pattern of copper (Cu) and molybdenum (Mo) formed by etchingwith an etching solution according to the present invention is viewedwith a scanning electron microscope (SEM).

[0054]FIG. 4A is a cross-sectional scanning electron microscope (SEM)image showing a pattern of copper (Cu) and molybdenum (Mo) formed byetching with an etching solution according to an embodiment of thepresent invention, FIG. 4B is a perspective scanning electron microscope(SEM) image showing a pattern of copper (Cu) and molybdenum (Mo) formedby etching with an etching solution according to an embodiment of thepresent invention, and FIG. 4C is a perspective scanning electronmicroscope (SEM) image showing a substrate after etching with an etchingsolution according to an embodiment of the present invention. Measuredetching speeds are about 50 Å/sec and about 7 Å/sec for copper (Cu) andmolybdenum (Mo), respectively.

[0055] As shown in FIGS. 4A and 4B, the pattern of copper (Cu) andmolybdenum (Mo) has an excellent profile and straightness. Moreover, asshown in FIG. 4C, no molybdenum (Mo) residues are observed on thesubstrate.

[0056] Table 1 illustrates etching speeds of copper (Cu) and molybdenum(Mo) obtained by etching with etching solutions having differentcomposition ratio according to embodiments of the present invention.TABLE 1 Compositions (weight %) (hydrogen peroxide/organic Etching speed(Å/sec) acid/phosphate/first Multiple layer additive/second additive/Single of Cu and Mo fluoric compound) layer of Cu Cu Mo No. 110/2/1/0.5/0.5/0.05 40˜60 40˜60 6˜8  No. 2 10/5/1/0.5/0.5/0.1 60˜9060˜90 5˜8  No. 3 5/0.5/0.2/0.2/0.2/0.01 20˜40 20˜40 4˜6  No. 410/1/1/0.5/0.2/0.01 40˜60 40˜60 6˜8  No. 5 12/2/2/0.5/1/0.1 50˜80 50˜806˜8  No. 6 12/2/5/1/1/0.1 70˜90 70˜90 6˜8  No. 7 15/2/1/0.5/1/0.1 60˜9060˜90 9˜12 No. 8 15/2/2/5/2/0.1 40˜60 40˜60 9˜12 No. 9 15/2/2/1/5/0.1 70˜100  70˜100 8˜11 No. 10 17/2/1/0.5/1/0.2 60˜90 60˜90 8˜11 No. 1117/2/2/0.5/0.5/0.1 60˜90 60˜90 9˜11 No. 12 20/2/1/2/1/0.1  90˜110 90˜110 10˜12  No. 13 20/5/5/5/5/0.2  80˜120  80˜120 12˜15  No. 1425/2/1/0.5/1/0.1 100˜120 100˜120 10˜12  No. 15 25/1/1/0.5/0.1/0.1 90˜110  90˜110 9˜11 No. 16 25/2/2/2/2/0.1  90˜110  90˜110 10˜12  No. 1725/2/1/0.5/1/0.5 100˜120 100˜120 10˜12  No. 18 25/2/1/0.5/1/1 100˜120100˜120 11˜14  No. 19 30/1/0.5/0.5/0.5/0.1 100˜120 100˜120 10˜12 

[0057] As illustrated in Table 1, the etching speed is determined by theamount of hydrogen peroxide and the amount of the first additiveincluding nitrogen. Since all compositions illustrated in Table 1 havesufficient etching speeds, the etching solutions having the compositionscan be applied to the etching process of the multiple layers of copper(Cu) and molybdenum (Mo).

[0058] With reference to Table 1, the amount of each ingredient isillustrated. Hydrogen peroxide is a main ingredient etching copper (Cu)and molybdenum (Mo). If an etching solution includes hydrogen peroxideless than about 5% by weight, the etching speed is too low and a processtime is too long. Accordingly, a reduction in processing time and anexcellent profile are obtained by using an etching solution includingabout 5% to 30% by weight of hydrogen peroxide.

[0059] Organic acid controls the pH of an etching solution. If anetching solution includes organic acid less than about 0.5% by weight,the amount of organic acid is too small to control pH value of theetching solution, and the etching solution does not maintain optimum pHvalue of about 0.5 to about 4.5. Accordingly, an etching solutionincluding about 0.5% to 5% by weight of organic acid maintains anoptimum pH value of about 0.5 to about 4.5.

[0060] Phosphate prevents an undercut by reducing an electric reactionof copper (Cu) and molybdenum (Mo). If an etching solution includesphosphate less than about 0.2% by weight, an undercut may occur.Accordingly, an excellent taper profile is obtained by using an etchingsolution including about 0.2% to 5% by weight of phosphate.

[0061] The first additive including nitrogen controls etching speed andreduces CD loss. The process margin is determined by the CD loss, andthe transmission of electric signals depends on the CD loss. Especially,since a TFT-LCD using a conductive line of a multiple layer of copper(Cu) and molybdenum (Mo) is fabricated to have a large panel size andhigh brightness, the transmission of electric signals without time delayand interference is a main subject. Moreover, as the CD loss increases,probabilities of straightness reduction and degradation in a subsequentprocess increase. If an etching solution includes the first additiveless than about 0.2% by weight, a CD loss is over 5% of a pattern sothat an excellent pattern can not be obtained. Accordingly, a reduced CDloss and an excellent taper profile is obtained by using an etchingsolution including about 0.2% to 5% by weight of the first additiveincluding nitrogen.

[0062] The second additive including nitrogen increases a storing timeof an etching solution and maintains a uniform etching property of anetching solution even after the etching solution is used many times. Ingeneral, it is hard to store a solution including hydrogen peroxide fora long time due to a self-decomposition reaction of hydrogen peroxide.Moreover, copper (Cu) ions form a passivation layer. The passivationlayer is oxidized to have black color, and the oxidized passivationlayer of copper (Cu) ions is not etched with an etching solution. Thesecond additive lengthens the storage time of an etching solution byreducing self-decomposition of hydrogen peroxide and prevents formationof a passivation layer by reducing activation of copper (Cu) ionsthrough chelation reaction. If an etching solution includes the secondadditive less than about 0.2% by weight, a passivation layer is formedafter etching, for example, about 500 substrates so that a sufficientutilization of the etching solution can not be obtained. Accordingly, asufficient storing time and a sufficient utilization are obtained byusing an etching solution including about 0.2% to 5% by weight of thesecond additive.

[0063] A fluoric compound removes molybdenum (Mo) residues generated inan etching solution having a pH value of about 0.5 to about 4.5. Themolybdenum (Mo) residues cause an electrical short and degradation ofconductive lines, thereby reducing brightness. If an etching solutionincludes fluoric acid less than about 0.01% by weight, molybdenum (Mo)residues remain as shown in FIG. 2C. Accordingly, molybdenum (Mo)residues are prevented without damaging layers including silicon byusing an etching solution including about 0.01% to about 1.0% by weightof fluoric compound.

[0064]FIG. 5A is a plane view showing an array substrate for a liquidcrystal display device fabricated using an etching solution according toan embodiment of the present invention and FIG. 5B is a cross-sectionalview taken along the line “VB-VB” of FIG. 5A.

[0065] In FIGS. 5A and 5B, a gate line 110 and a gate electrode 112 areformed on a substrate 100. A buffer layer of an insulating material maybe formed between the substrate 100 and the gate line 110 and a cleaningprocess may be performed before forming the gate line 110. A gateinsulating layer 114 is formed on the gate line 110 and the gateelectrode 112. An active layer 120 of a semiconductor material such asamorphous silicon is formed on the gate insulating layer 114 over thegate electrode 112, and an ohmic contact layer 122 of an impurity dopedsemiconductor material is formed on the active layer 120.

[0066] A data line 130 and a storage electrode 136 are formed on thegate insulating layer 114 and a source electrode 132 and a drainelectrode 134 are formed on the ohmic contact layer 122. The data line130 crosses the gate line 110 to define a pixel region “P” and thesource 132 and drain electrodes 134 are spaced apart from each other.The storage electrode 136 overlaps a portion of the gate line 110 toconstitute a storage capacitor “CST.” The data line 130, the sourceelectrode 132, the drain electrode 134 and the storage electrode 136 maybe simultaneously formed of a multiple layer of copper (Cu) andmolybdenum (Mo) using an etching solution including hydrogen peroxide,organic acid, phosphate, a first additive, a second additive, a fluoriccompound and de-ionized water. In other words, the data line 130includes a data molybdenum (Mo) layer 130 a and a data copper (Cu) layer130 b, the source electrode 132 includes a source molybdenum (Mo) layer132 a and a source copper (Cu) layer 132 b, and the drain electrode 134includes a drain molybdenum (Mo) layer 134 a and a drain copper (Cu)layer 134 b, and the storage electrode 136 includes a storage molybdenum(Mo) layer 136 a and a storage copper (Cu) layer 136 b. Each of the dataline 130, the source electrode 132, the drain electrode 134 and thestorage electrode 136 has a taper profile with a substantially smallamount of molybdenum (Mo) residues after etching, thereby improvingcharacteristics of a liquid crystal display device.

[0067] A passivation layer 138 of an insulating material is formed onthe data line 130, the source electrode 132, the drain electrode 134 andthe storage electrode 136 and a pixel electrode 140 is formed on thepassivation layer 138. The pixel electrode 140 is connected to the drainelectrode 134 and the storage electrode 136.

[0068] In this embodiment, only the data line 130, the source electrode132, the drain electrode 134 and the storage electrode 136 are formed ofa multiple layer of copper (Cu) and molybdenum (Mo) as shown in FIGS. 5Aand 5B. However, it should be understood that the gate line 110 and thegate electrode 112 may be formed of a multiple layer of copper (Cu) andmolybdenum (Mo). Moreover, in this embodiment, a double layer of copper(Cu) and molybdenum (Mo) is used for the data line 130, the sourceelectrode 132, the drain electrode 134 and the storage electrode 136 asshown in FIGS. 5A and 5B. It should be further understood that amultiple layer including more than two layers of copper (Cu) andmolybdenum (Mo) may be used. A copper (Cu) layer and a molybdenum (Mo)layer may be formed by a physical vapor deposition (PVD) method using asputter. In addition, an etching solution according to the presentinvention may be used for etching a single layer of copper (Cu).

[0069] In sum, an etching solution and an etching method using theetching solution according to the present invention have severaladvantages.

[0070] Etching speed can be easily controlled, and an excellent taperprofile having a taper angle of about 30° to about 60° and an excellentstraightness of conductive lines are obtained. In addition, an etchingsolution maintains a uniform etching property such as etching speed evenafter the etching solution is used many times. The etching solution canbe stored for a long time period without change of etching property.Moreover, since molybdenum (Mo) residues generated in an etchingsolution having a pH value of about 0.5 to about 4.5 do not remain,electrical shorts and line defects are prevented. Thus, the brightnessof an LCD device is improved. Therefore, a large-size LCD device havinga high brightness is obtained by etching a multiple layer of copper (Cu)and molybdenum (Mo) with an etching solution according to the presentinvention.

[0071] It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An etching solution for a multiple layer ofcopper and molybdenum, comprising: about 5% to about 30% by weight of ahydrogen peroxide; about 0.5% to about 5% by weight of an organic acid;about 0.2% to about 5% by weight of a phosphate; about 0.2% to about 5%by weight of a first additive having nitrogen; about 0.2% to about 5% byweight of a second additive having nitrogen; about 0.01% to about 1.0%by weight of a fluoric compound; and de-ionized water making a totalamount of the etching solution 100% by weight.
 2. The etching solutionaccording to claim 1, wherein the organic acid is water-soluble.
 3. Theetching solution according to claim 2; wherein the organic acid isselected from a group consisting of acetic acid, butanoic acid, citricacid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalicacid and pentanoic acid.
 4. The etching solution according to claim 1,wherein the phosphate is a salt obtained by substituting at least onehydrogen of phosphoric acid with one of alkali metal and alkaline earthmetal.
 5. The etching solution according to claim 4, wherein thephosphate is selected from a group consisting of sodium dihydrogenphosphate and potassium dihydrogen phosphate.
 6. The etching solutionaccording to claim 1, wherein the first additive is a water-solublecyclic amine compound.
 7. The etching solution according to claim 6,wherein the first additive is selected from a group consisting ofaminotetrazole, imidazole, indole, purine, pyrazole, pyridine,pyrimidine, pyrrole, pyrrolidine, pyrroline.
 8. The etching solutionaccording to claim 1, wherein the second additive is a water-solublecompound including one of amino group and carboxyl group.
 9. The etchingsolution according to claim 8, wherein the second additive is selectedfrom a group consisting of alanine, aminobutyric acid, glutamic acid,glycine, iminodiacetic acid, nitrilotriacetic acid, sarcosine and theirderivatives.
 10. The etching solution according to claim 1, wherein thefluoric acid is a compound capable of being dissociated into one offluoric ion and polyatomic fluoric ion in the etching solution.
 11. Theetching solution according to claim 10, wherein the second additive isselected from a group consisting of ammonium fluoride, sodium fluoride,potassium fluoride, ammonium bifluoride, sodium bifluoride and potassiumbifluoride.
 12. The etching solution according to claim 1, wherein themultiple layer is a double layer including a lower molybdenum layer andan upper copper layer.
 13. An etching method for a multiple layer ofcopper and molybdenum, comprising: forming the multiple layer of copperand molybdenum on a substrate; forming a photoresist pattern on themultiple layer; and etching the multiple layer with an etching solutionincluding: about 5% to about 30% by weight of a hydrogen peroxide; about0.5% to about 5% by weight of an organic acid; about 0.2% to about 5% byweight of a phosphate; about 0.2% to about 5% by weight of a firstadditive having nitrogen; about 0.2% to about 5% by weight of a secondadditive having nitrogen; about 0.01% to about 1.0% by weight of afluoric compound; and de-ionized water making a total amount of theetching solution 100% by weight.
 14. The method according to claim 13,wherein the multiple layer is a double layer including a lowermolybdenum layer and an upper copper layer.
 15. The method according toclaim 14, wherein the upper copper layer is thicker than the lowermolybdenum layer.
 16. The method according to claim 13, wherein thesubstrate is a glass substrate for a liquid crystal display device. 17.The method according to claim 13, wherein the multiple layer is used asa data line for a liquid crystal display device.
 18. A composition foretching a multiple layer of copper and molybdenum, comprising: about 5%to about 30% by weight of a hydrogen peroxide; about 0.5% to about 5% byweight of an organic acid; about 0.2% to about 5% by weight of aphosphate; about 0.2% to about 5% by weight of a first additive havingnitrogen; about 0.2% to about 5% by weight of a second additive havingnitrogen; about 0.01% to about 1.0% by weight of a fluoric compound; andabout 45% to about 93.89% by weight of de-ionized water.
 19. Thecomposition according to claim 18, wherein the organic acid controls apH value of the composition.
 20. The composition according to claim 18,wherein the phosphate reduces an electric effect between copper andmolybdenum.
 21. The composition according to claim 18, wherein the firstadditive controls an etch speed of the composition.
 22. The compositionaccording to claim 18, wherein the second additive reduces aself-decomposition reaction of the hydrogen peroxide.
 23. Thecomposition according to claim 18, wherein the second additive reducesactivation of copper and molybdenum ions.
 24. The composition accordingto claim 18, wherein the fluoric acid removes molybdenum residues.
 25. Amethod of fabricating an array substrate for a liquid crystal displaydevice, comprising: forming a gate electrode and a gate line on asubstrate; forming a first insulating layer on the gate electrode andthe gate line; forming a semiconductor layer on the first insulatinglayer; and forming source and drain electrodes on the semiconductorlayer and a data line crossing the gate line, the source and drainelectrode being spaced apart from each other, the source electrode beingconnected to the data line, the gate line and the data line defining apixel region, wherein at least one of the gate line and the data line isa multiple layer of copper and molybdenum, and the etching of themultiple layer is performed with an etching solution including: about 5%to about 30% by weight of a hydrogen peroxide; about 0.5% to about 5% byweight of an organic acid; about 0.2% to about 5% by weight of aphosphate; about 0.2% to about 5% by weight of a first additive havingnitrogen; about 0.2% to about 5% by weight of a second additive havingnitrogen; about 0.01% to about 1.0% by weight of a fluoric compound; anda de-ionized water making a total amount of the etching solution 100% byweight.
 26. The method according to claim 25, wherein the multiple layeris a double layer including a lower molybdenum layer and an upper copperlayer.
 27. The method according to claim 26, wherein the upper copperlayer is thicker than the lower molybdenum layer.